Distribution and seasonal abundance of <i>Oscillatoria nigroviridis</i> Thwaites ex. Gomant in the waters of Visakhapatnam

Abstract

<i>O. nigroviridis</i> and other blue-green algae are abundant in the waters of harbour area indicating the polluted nature of the Visakhapatnam Harbour. In the surface waters of 4 stations, standing crop of <i>O. nigroviridis</i> varies in all months of the year with 2 peaks, a primary peak between September and December and a secondary peak between January and April. Production of <i>O. nigroviridis</i> is higher in the sewage polluted waters of station 1 than in the waters of other 3 stations, which are relatively less polluted.